The present invention has particular application for building up and discharging an annular dump of bulk material at a circular storage site.
The prior known apparatus for handling bulk material as located at a storage site have included several versions of the well known stacker-reclaimer apparatus, and two of such kinds of equipment are illustrated in the U.S. Patents to STROCKER, U.S. Pat. No. 3,472,357 and FISHER, U.S. Pat. No. 3,509,985. Both the STROCKER and FISHER patents disclose equipment that includes a device for receiving bulk material from a feed conveyor and for conveying and dumping the bulk material onto a pile at the storage device. The usual scraper reclaimer devices are also disclosed in these prior known constructions for removing the bulk material from the stored piles for transfer to a remote location. In other versions of stacker-reclaimers, the equipment included a support structure that was mounted on wheels for travel along elongated tracks on both sides of which the bulk material was deposited in stored piles. The stacking mechanism and the scraper reclaimer devices were both pivotally mounted on the traveling structure and were rotated therewith. In the apparatus as shown in the STROCKER patent, both the stacker and the scraper reclaimer devices are also pivotally mounted with respect to the main frame of the apparatus, and in this manner are able to stack the bulk material and reclaim it from the stacked pile as required. However, this equipment as constructed was not practical for simultaneous stacking and reclaiming of the bulk material. In the FISHER patent, the piles of material are arranged in piles relative to a stationary central column, and the stacker and reclaimer are rotated relative to the stationary column for both stacking the bulk material and reclaiming it as required. The FISHER apparatus also includes a fixed hopper that is mounted under the column for receiving the bulk material from the scraper reclaimer device for transfer to a remote location. However, the hopper has spokes fixed thereto that support the column; and as a result, the hopper is obstructed and the material tends to clog the hopper as it is deposited therein. Further, the reclaimer and stacker devices in this construction cannot pass each other, but must still work on material arrayed in a 360.degree. pile, requiring complex and expensive equipment, including an undergound discharge conveyor. The FISHER construction also requires that the feed end of the feed conveyor be supported by the central column which further requires a complex bearing arrangement that additionally increases the cost of the unit.
Both the bulk material handling apparatus as illustrated in the STROCKER and FISHER patents were useful in certain environments, but were limited in the application thereof because of the bulky equipment used and space requirements therefor. Further the heavy loads as carried by the scraper conveyor apparatus illustrated in the STROCKER patent, required that the stacker and scraper reclaimer devices utilized therein be cantilevered in a manner so as to effectively offset each other. Locating these devices on a central column as shown in the STROCKER patent had its inherent disadvantages; and because of cost factors, the STROCKER scraper-conveyor apparatus could only be used in special applications. Similarly, the FISHER conveyor loading and unloading apparatus are quite complex in the structural arrangement thereof and, as a result, the economic factors dictated that the FISHER apparatus could only be used in those locations that would warrant the installation of that kind of equipment. Another system known to applicants but having limited commercial use included a tower construction having a truss structure on which a stacker device was supported for conveying bulk material to a pile. Offset from the tower was a reclaimer device that was supported by the tower; but because the reclaimer device had limited rotational movement relative to the tower, this system had only limited application.
Some efforts were made by the applicants herein to provide a relatively simplified device for building up and discharging an annular dump of bulk material at a circular storage site, and this device is illustrated in U.S. Pat. No. 4,363,396. As shown in U.S. Pat. No. 4,363,396, a scraper reclaimer device and a stacker device are mounted on a rotating column for movement with and relative thereto, respectively; and the material as recovered by the scraper reclaimer device is deposited into a hopper that is unobstructed at the receiving end thereof, this kind of hopper being contrary to the kind of hopper shown in the earlier described FISHER patent. However, because of certain limitations with respect to the costs embodied in the device shown in U.S. Pat. No. 4,363,396, the device also had some limitations in use; although, as an operating mechanism, it has found favor in the trade. It was because of economic considerations and the facility of use thereof that the subject invention was developed, and in this respect does present an alternative to the device shown in U.S. Pat. No. 4,363,396.